An automobile body is formed by joining a plurality of panel materials by spot welding, and it is necessary to position and clamp various panel materials configuring the automobile body in performing the spot welding. Therefore, in order to position and clamp the panel materials, a plurality of positioning and clamping apparatuses are attached to a welding stage arranged in an automobile manufacturing line. On a conveying truck which conveys the panel materials, as described in Patent Documents 1 (Japanese Patent Application Laid-Open Publication No. 2003-159617) and 2 (Japanese Patent Application Laid-Open Publication No. 2003-165037), the plurality of positioning and clamping apparatuses are mounted in order to clamp the panel materials. Further, positioning and clamping of the panel materials by the positioning and clamping apparatus are performed by mounting the positioning and clamping apparatus to a tip of a robot arm to operate and move the robot arm.
In each of above cases, the conventional positioning and clamping apparatus has the locating pin which is fitted in a positioning hole formed in the panel material as a workpiece, and the panel material is intended to be positioned by fitting the locating pin into the positioning hole. A clamp arm is assembled in a slit formed in the locating pin in order to clamp the panel material, so that when the panel material is clamped, the clamp arm is caused to protrude from an interior of the slit.